title: The mixture of "ecstasy" and its metabolites is toxic to human SH-SY5Y differentiated cells at in vivo relevant concentrations.
abstract: The neurotoxicity of "ecstasy" (3,4-methylenedioxymethamphetamine, MDMA) is thought to involve hepatic metabolism, though its real contribution is not completely understood. Most in vitro neurotoxicity studies concern isolated exposures of MDMA or its metabolites, at high concentrations, not considering their mixture, as expected in vivo. Therefore, our postulate is that combined deleterious effects of MDMA and its metabolites, at low micromolar concentrations that may be attained into the brain, may elicit neurotoxicity. Using human SH-SY5Y differentiated cells as dopaminergic neuronal model, we studied the neurotoxicity of MDMA and its MDMA metabolites α-methyldopamine and N-methyl-α-methyldopamine and their correspondent glutathione and N-acetylcysteine monoconjugates, under isolated exposure and as a mixture, at normothermic or hyperthermic conditions. The results showed that the mixture of MDMA and its metabolites was toxic to SH-SY5Y differentiated cells, an effect potentiated by hyperthermia and prevented by N-acetylcysteine. As a mixture, MDMA and its metabolites presented a different toxicity profile, compared to each compound alone, even at equimolar concentrations. Caspase 3 activation, increased reactive oxygen species production, and intracellular Ca(2+) raises were implicated in the toxic effect. The mixture increased intracellular glutathione levels by increasing its de novo synthesis. In conclusion, this study demonstrated, for the first time, that the mixture of MDMA and its metabolites, at low micromolar concentrations, which represents a more realistic approach of the in vivo scenario, elicited toxicity to human SH-SY5Y differentiated cells, thus constituting a new insight into the context of MDMA-related neurotoxicity.
authors.affiliation: REQUIMTE (Rede de Química e Tecnologia), Toxicology Laboratory, Department of Biological Sciences, Faculty of Pharmacy, University of Porto, Rua Jorge Viterbo Ferreira 228, 4050-313, Porto, Portugal, daniel.barbosa@ff.up.pt.
authors.forename: Daniel José
authors.initials: DJ
authors.lastname: Barbosa
authors.forename: João Paulo
authors.initials: JP
authors.lastname: Capela
authors.forename: Renata
authors.initials: R
authors.lastname: Silva
authors.forename: Vânia
authors.initials: V
authors.lastname: Vilas-Boas
authors.forename: Luísa Maria
authors.initials: LM
authors.lastname: Ferreira
authors.forename: Paula Sério
authors.initials: PS
authors.lastname: Branco
authors.forename: Eduarda
authors.initials: E
authors.lastname: Fernandes
authors.forename: Maria de Lourdes
authors.initials: Mde L
authors.lastname: Bastos
authors.forename: Félix
authors.initials: F
authors.lastname: Carvalho
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line / Q000187:drug effects; D003846:Deoxyepinephrine / Q000031:analogs & derivatives / Q000633:toxicity; D004298:Dopamine / Q000378:metabolism / Q000493:pharmacokinetics; D059290:Dopaminergic Neurons / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D018817:N-Methyl-3,4-methylenedioxyamphetamine / Q000008:administration & dosage / Q000378:metabolism / Q000633:toxicity*; D009474:Neurons / Q000187:drug effects* / Q000473:pathology; D020258:Neurotoxicity Syndromes / Q000473:pathology; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; C023492:alpha-methyldopamine; D053148:Caspase 3; D005978:Glutathione; D018817:N-Methyl-3,4-methylenedioxyamphetamine; D003846:Deoxyepinephrine; D002118:Calcium; D004298:Dopamine; D000111:Acetylcysteine